It is frequently necessary to transport patients to or from a hospital or from one area within a health care facility to another part of the health care facility. In transporting patients, operators (usually two Emergency Medical Technicians) are routinely required to physically lift the transporter carrying the patient. This places the operators at a high risk of significant and even crippling back injuries, particularly in the field where regular hospital facilities are not available.
The transporters used to move patients from one location to another within a health care facility are frequently expensive, heavy duty devices which are unsatisfactory for use in the field. These intra-hospital transporters usually must be connected to an electrical outlet in order to adjust the position or height of the transporter for the patient's comfort or for transferring the patient to or from an operating table or other medical apparatus.
While various attempts have been made to reduce the back stress and the risk of back injury to transporter operators, no lightweight, compact, cost effective, and adaptable power-assisted mobile patient transporter is presently available. Present power-assisted lifting mechanisms for transporters typically suffer from the following or similar disadvantages:
a. In U.S. Pat. No. 5,022,105, entitled "Mobile Lift-Assisted Transport Device For Field Use", a lifting mechanism powered by high-pressure compressed air or oxygen is used to adjust the height of a transporter. However, compressed air is not readily available to operators, and compressed oxygen is expensive and poses an added risk to the patient and the operators in hazardous emergency situations. Also, compressed air or oxygen cylinders are heavy and cumbersome. PA1 b. In U.S. Pat. No. 2,833,587, entitled "Adjustable Height Gurney", a manually powered hydraulic lifting mechanism is used to raise or lower the bed frame of a transporter. Such a manual hydraulic system is both slow and relatively heavy. Moreover, using a battery powered hydraulic system, which includes one or more hydraulic cylinders, a hydraulic pump and pump motor, high pressure fittings and hoses, controls, and a relatively large battery unduly increases the weight of the transporter. PA1 c. A transporter lifting mechanism using an acme or trapezoidal lead screw is inefficient, since these types of lead screws require considerable force to overcome the inherent sliding friction of the lead screw threads against the nut. Thus, relatively large motors are required to provide sufficient torque. If a battery powered electric motor is used to drive such a lifting mechanism, relatively large batteries are required and battery life is reduced.
There are a large number of existing, manually operated transporters currently in use. Any power-assisted lift mechanism which cannot be adapted to an existing transporter, but would instead require the purchase of a new transporter having a built-in power lifting unit, would needlessly increase the cost of medical care.